Specifying the wrong plywood thickness is one of the most common material mistakes in Indian furniture production. Too thin and you get structural failure. Too thick and you waste money with no benefit.
The Complete Thickness Reference
| Component | Thickness | Grade Needed |
|---|---|---|
| Kitchen carcass (sides, base, top) | 18mm | IS:710 BWP |
| Kitchen internal shelves | 12mm | IS:710 BWP |
| Kitchen back panel | 6mm | HMR board |
| Wardrobe carcass (sides, base, top, verticals) | 18mm | IS:303 or IS:710 |
| Wardrobe internal shelves | 12mm | IS:303 |
| Wardrobe back panel | 6mm | Standard |
| Drawer bottoms | 6mm | HMR (for kitchen), standard (wardrobe) |
| TV unit carcass | 18mm | IS:303 |
| Bed frame | 18mm | IS:303 |
| Study desk top | 18mm or 25mm | IS:303 (25mm for wide spans) |
| Door shutters | 18mm blockboard | IS:303 Blockboard |
| Bookshelf (long span 1.2m+) | 19mm blockboard | Prevents sagging |
Why 18mm Is the Magic Number
18mm is the Indian furniture industry standard for carcass thickness because:
- It provides enough material for a strong screw bite (at least 12mm entry depth)
- It can span up to 900mm without significant sag under normal shelf load
- It’s the size that CNC machines and hardware (hinges, channels) are designed to accommodate
Going below 18mm on the main structure = compromised screw holding, visible flex under load, premature joint failure.
When to Use 25mm
25mm makes sense for:
- Desktop surfaces that span over 1.2m width and bear typing/equipment load
- Heavy kitchen base shelves bearing stone mortar or cast iron cookware
- Long bookshelf spans over 1.5m (though blockboard is often better here)
The Back Panel Exception
6mm back panels are the correct and intended specification. They don’t carry any load � they simply close the box and prevent racking. Using 12mm back panels is expensive and unnecessary. Using anything less than 6mm risks the panel warping or cracking.